Actually, you may already know him quite well. He is the 16-year-old, good-looking, Canadian-born pop/R&B singer best known for hit singles like "Baby" and "Never Let You Go." He may not have founded the world's largest social networking site after dropping out of Harvard University, as Zuckerberg did, but he is capable of making 14-, 15- and 16-year-olds—actually, make that the majority of tweens and young women—swoon and faint at his concerts just at the mere sound of his voice. He is, to stop the suspense, Justin Bieber.

Though not yet Time's Person of the Year—hey, one never knows—Bieber easily topped celebrities like Joe and Nick Jonas and Lady Gaga as this year's most influential Twitter celebrity, per a Klout study compiled for Forbes. The research firm ranked individuals based on their klout, or social media influence, which is basically a measure of the "impact of your opinions, links and recommendations across your social graph," as the company defines it.

The higher the klout score, the more influential the celebrity.Bieber came in with a perfect score of 100. His next nearest contender, Brazilian novelist Paulo Coelho, earned a klout score of 96. Joe Jonas, a member of the popular pop-rock trio, the Jonas Brothers, is in third place with a score of 92. The klout score is compiled using an algorithm that takes into account 35 factors, including a celebrity's number of retweets and followers.

The findings, indeed, hold some implications for marketers. A celebrity can lend some credibility, not to mention star power, to one's campaign. Imagine snagging Bieber, who reaches 6 million-plus followers via his Twitter handle, @justinbieber, to endorse your product. A single tweet can generate a butterfly effect of "oohhs" and "aahhs" among loyal fans. But Megan Berry, marketing manager at Klout, says advertisers should still take precautions.

Just because a celebrity has klout doesn't mean he/she will lend the magic touch to sales or a campaign, Berry says. Marketers also must take into consideration how much one's brand actually aligns with said celebrity. Consider Lady Gaga. "We know she can produce a lot of attention for your brand, but if she's endorsing a conservative product, that might not necessarily fit with her brand," she says, referring to the popular notion of celebrities as "brands." Bottom line: "It can push a lot of attention, but we're not sure whether that attention will end up as ROI," Berry admits.

In the meantime, all you Bieber haters might want to check out who else made the rankings. Here are Klout's top 20. Celebrities are listed by their Twitter handles plus corresponding klout score.